ip.c revision 329423 
1/*
2 * Copyright (c) 1992 Regents of the University of California.
3 * All rights reserved.
4 *
5 * This software was developed by the Computer Systems Engineering group
6 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
7 * contributed to Berkeley.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34/*
35 * The send and receive functions were originally implemented in udp.c and
36 * moved here. Also it is likely some more cleanup can be done, especially
37 * once we will implement the support for tcp.
38 */
39
40#include <sys/cdefs.h>
41__FBSDID("$FreeBSD: stable/11/stand/libsa/ip.c 329423 2018-02-17 02:14:01Z kevans $");
42
43#include <sys/param.h>
44#include <sys/socket.h>
45#include <sys/queue.h>
46
47#include <string.h>
48
49#include <net/if.h>
50#include <netinet/in.h>
51#include <netinet/if_ether.h>
52#include <netinet/in_systm.h>
53
54#include <netinet/in_pcb.h>
55#include <netinet/ip.h>
56#include <netinet/ip_var.h>
57#include <netinet/udp.h>
58#include <netinet/udp_var.h>
59
60#include "stand.h"
61#include "net.h"
62
63typedef STAILQ_HEAD(ipqueue, ip_queue) ip_queue_t;
64struct ip_queue {
65	void		*ipq_pkt;
66	struct ip	*ipq_hdr;
67	STAILQ_ENTRY(ip_queue) ipq_next;
68};
69
70/*
71 * Fragment re-assembly queue.
72 */
73struct ip_reasm {
74	struct in_addr	ip_src;
75	struct in_addr	ip_dst;
76	uint16_t	ip_id;
77	uint8_t		ip_proto;
78	uint8_t		ip_ttl;
79	size_t		ip_total_size;
80	ip_queue_t	ip_queue;
81	void		*ip_pkt;
82	struct ip	*ip_hdr;
83	STAILQ_ENTRY(ip_reasm) ip_next;
84};
85
86STAILQ_HEAD(ire_list, ip_reasm) ire_list = STAILQ_HEAD_INITIALIZER(ire_list);
87
88/* Caller must leave room for ethernet and ip headers in front!! */
89ssize_t
90sendip(struct iodesc *d, void *pkt, size_t len, uint8_t proto)
91{
92	ssize_t cc;
93	struct ip *ip;
94	u_char *ea;
95
96#ifdef NET_DEBUG
97	if (debug) {
98		printf("sendip: proto: %x d=%p called.\n", proto, (void *)d);
99		if (d) {
100			printf("saddr: %s:%d",
101			    inet_ntoa(d->myip), ntohs(d->myport));
102			printf(" daddr: %s:%d\n",
103			    inet_ntoa(d->destip), ntohs(d->destport));
104		}
105	}
106#endif
107
108	ip = (struct ip *)pkt - 1;
109	len += sizeof(*ip);
110
111	bzero(ip, sizeof(*ip));
112
113	ip->ip_v = IPVERSION;			/* half-char */
114	ip->ip_hl = sizeof(*ip) >> 2;		/* half-char */
115	ip->ip_len = htons(len);
116	ip->ip_p = proto;			/* char */
117	ip->ip_ttl = IPDEFTTL;			/* char */
118	ip->ip_src = d->myip;
119	ip->ip_dst = d->destip;
120	ip->ip_sum = in_cksum(ip, sizeof(*ip));	 /* short, but special */
121
122	if (ip->ip_dst.s_addr == INADDR_BROADCAST || ip->ip_src.s_addr == 0 ||
123	    netmask == 0 || SAMENET(ip->ip_src, ip->ip_dst, netmask))
124		ea = arpwhohas(d, ip->ip_dst);
125	else
126		ea = arpwhohas(d, gateip);
127
128	cc = sendether(d, ip, len, ea, ETHERTYPE_IP);
129	if (cc == -1)
130		return (-1);
131	if (cc != len)
132		panic("sendip: bad write (%zd != %zd)", cc, len);
133	return (cc - sizeof(*ip));
134}
135
136static void
137ip_reasm_free(struct ip_reasm *ipr)
138{
139	struct ip_queue *ipq;
140
141	while ((ipq = STAILQ_FIRST(&ipr->ip_queue)) != NULL) {
142		STAILQ_REMOVE_HEAD(&ipr->ip_queue, ipq_next);
143		free(ipq->ipq_pkt);
144		free(ipq);
145	}
146	free(ipr->ip_pkt);
147	free(ipr);
148}
149
150static int
151ip_reasm_add(struct ip_reasm *ipr, void *pkt, struct ip *ip)
152{
153	struct ip_queue *ipq, *prev, *p;
154
155	if ((ipq = calloc(1, sizeof (*ipq))) == NULL)
156		return (1);
157
158	ipq->ipq_pkt = pkt;
159	ipq->ipq_hdr = ip;
160
161	prev = NULL;
162	STAILQ_FOREACH(p, &ipr->ip_queue, ipq_next) {
163		if ((ntohs(p->ipq_hdr->ip_off) & IP_OFFMASK) <
164		    (ntohs(ip->ip_off) & IP_OFFMASK)) {
165			prev = p;
166			continue;
167		}
168		if (prev == NULL)
169			break;
170
171		STAILQ_INSERT_AFTER(&ipr->ip_queue, prev, ipq, ipq_next);
172		return (0);
173	}
174	STAILQ_INSERT_HEAD(&ipr->ip_queue, ipq, ipq_next);
175	return (0);
176}
177
178/*
179 * Receive a IP packet and validate it is for us.
180 */
181static ssize_t
182readipv4(struct iodesc *d, void **pkt, void **payload, time_t tleft,
183    uint8_t proto)
184{
185	ssize_t n;
186	size_t hlen;
187	struct ether_header *eh;
188	struct ip *ip;
189	struct udphdr *uh;
190	uint16_t etype;		/* host order */
191	char *ptr;
192	struct ip_reasm *ipr;
193	struct ip_queue *ipq, *last;
194
195#ifdef NET_DEBUG
196	if (debug)
197		printf("readip: called\n");
198#endif
199
200	ip = NULL;
201	ptr = NULL;
202	n = readether(d, (void **)&ptr, (void **)&ip, tleft, &etype);
203	if (n == -1 || n < sizeof(*ip) + sizeof(*uh)) {
204		free(ptr);
205		return (-1);
206	}
207
208	/* Ethernet address checks now in readether() */
209
210	/* Need to respond to ARP requests. */
211	if (etype == ETHERTYPE_ARP) {
212		struct arphdr *ah = (void *)ip;
213		if (ah->ar_op == htons(ARPOP_REQUEST)) {
214			/* Send ARP reply */
215			arp_reply(d, ah);
216		}
217		free(ptr);
218		errno = EAGAIN;	/* Call me again. */
219		return (-1);
220	}
221
222	if (etype != ETHERTYPE_IP) {
223#ifdef NET_DEBUG
224		if (debug)
225			printf("readip: not IP. ether_type=%x\n", etype);
226#endif
227		free(ptr);
228		return (-1);
229	}
230
231	/* Check ip header */
232	if (ip->ip_v != IPVERSION ||	/* half char */
233	    ip->ip_p != proto) {
234#ifdef NET_DEBUG
235		if (debug) {
236			printf("readip: IP version or proto. ip_v=%d ip_p=%d\n",
237			    ip->ip_v, ip->ip_p);
238		}
239#endif
240		free(ptr);
241		return (-1);
242	}
243
244	hlen = ip->ip_hl << 2;
245	if (hlen < sizeof(*ip) ||
246	    in_cksum(ip, hlen) != 0) {
247#ifdef NET_DEBUG
248		if (debug)
249			printf("readip: short hdr or bad cksum.\n");
250#endif
251		free(ptr);
252		return (-1);
253	}
254	if (n < ntohs(ip->ip_len)) {
255#ifdef NET_DEBUG
256		if (debug)
257			printf("readip: bad length %d < %d.\n",
258			       (int)n, ntohs(ip->ip_len));
259#endif
260		free(ptr);
261		return (-1);
262	}
263	if (d->myip.s_addr && ip->ip_dst.s_addr != d->myip.s_addr) {
264#ifdef NET_DEBUG
265		if (debug) {
266			printf("readip: bad saddr %s != ", inet_ntoa(d->myip));
267			printf("%s\n", inet_ntoa(ip->ip_dst));
268		}
269#endif
270		free(ptr);
271		return (-1);
272	}
273
274	/* Unfragmented packet. */
275	if ((ntohs(ip->ip_off) & IP_MF) == 0 &&
276	    (ntohs(ip->ip_off) & IP_OFFMASK) == 0) {
277		uh = (struct udphdr *)((uintptr_t)ip + sizeof (*ip));
278		/* If there were ip options, make them go away */
279		if (hlen != sizeof(*ip)) {
280			bcopy(((u_char *)ip) + hlen, uh, uh->uh_ulen - hlen);
281			ip->ip_len = htons(sizeof(*ip));
282			n -= hlen - sizeof(*ip);
283		}
284
285		n = (n > (ntohs(ip->ip_len) - sizeof(*ip))) ?
286		    ntohs(ip->ip_len) - sizeof(*ip) : n;
287		*pkt = ptr;
288		*payload = (void *)((uintptr_t)ip + sizeof(*ip));
289		return (n);
290	}
291
292	STAILQ_FOREACH(ipr, &ire_list, ip_next) {
293		if (ipr->ip_src.s_addr == ip->ip_src.s_addr &&
294		    ipr->ip_dst.s_addr == ip->ip_dst.s_addr &&
295		    ipr->ip_id == ip->ip_id &&
296		    ipr->ip_proto == ip->ip_p)
297			break;
298	}
299
300	/* Allocate new reassembly entry */
301	if (ipr == NULL) {
302		if ((ipr = calloc(1, sizeof (*ipr))) == NULL) {
303			free(ptr);
304			return (-1);
305		}
306
307		ipr->ip_src = ip->ip_src;
308		ipr->ip_dst = ip->ip_dst;
309		ipr->ip_id = ip->ip_id;
310		ipr->ip_proto = ip->ip_p;
311		ipr->ip_ttl = MAXTTL;
312		STAILQ_INIT(&ipr->ip_queue);
313		STAILQ_INSERT_TAIL(&ire_list, ipr, ip_next);
314	}
315
316	if (ip_reasm_add(ipr, ptr, ip) != 0) {
317		STAILQ_REMOVE(&ire_list, ipr, ip_reasm, ip_next);
318		free(ipr);
319		free(ptr);
320		return (-1);
321	}
322
323	if ((ntohs(ip->ip_off) & IP_MF) == 0) {
324		ipr->ip_total_size = (8 * (ntohs(ip->ip_off) & IP_OFFMASK));
325		ipr->ip_total_size += n + sizeof (*ip);
326		ipr->ip_total_size += sizeof (struct ether_header);
327
328		ipr->ip_pkt = malloc(ipr->ip_total_size + 2);
329		if (ipr->ip_pkt == NULL) {
330			STAILQ_REMOVE(&ire_list, ipr, ip_reasm, ip_next);
331			ip_reasm_free(ipr);
332			return (-1);
333		}
334	}
335
336	/*
337	 * If we do not have re-assembly buffer ipr->ip_pkt, we are still
338	 * missing fragments, so just restart the read.
339	 */
340	if (ipr->ip_pkt == NULL) {
341		errno = EAGAIN;
342		return (-1);
343	}
344
345	/*
346	 * Walk the packet list in reassembly queue, if we got all the
347	 * fragments, build the packet.
348	 */
349	n = 0;
350	last = NULL;
351	STAILQ_FOREACH(ipq, &ipr->ip_queue, ipq_next) {
352		if ((ntohs(ipq->ipq_hdr->ip_off) & IP_OFFMASK) != n / 8) {
353			STAILQ_REMOVE(&ire_list, ipr, ip_reasm, ip_next);
354			ip_reasm_free(ipr);
355			return (-1);
356		}
357
358		n += ntohs(ipq->ipq_hdr->ip_len) - (ipq->ipq_hdr->ip_hl << 2);
359		last = ipq;
360	}
361	if ((ntohs(last->ipq_hdr->ip_off) & IP_MF) != 0) {
362		errno = EAGAIN;
363		return (-1);
364	}
365
366	ipq = STAILQ_FIRST(&ipr->ip_queue);
367	/* Fabricate ethernet header */
368	eh = (struct ether_header *)((uintptr_t)ipr->ip_pkt + 2);
369	bcopy((void *)((uintptr_t)ipq->ipq_pkt + 2), eh, sizeof (*eh));
370
371	/* Fabricate IP header */
372	ipr->ip_hdr = (struct ip *)((uintptr_t)eh + sizeof (*eh));
373	bcopy(ipq->ipq_hdr, ipr->ip_hdr, sizeof (*ipr->ip_hdr));
374	ipr->ip_hdr->ip_hl = sizeof (*ipr->ip_hdr) >> 2;
375	ipr->ip_hdr->ip_len = htons(n);
376	ipr->ip_hdr->ip_sum = 0;
377	ipr->ip_hdr->ip_sum = in_cksum(ipr->ip_hdr, sizeof (*ipr->ip_hdr));
378
379	n = 0;
380	ptr = (char *)((uintptr_t)ipr->ip_hdr + sizeof (*ipr->ip_hdr));
381	STAILQ_FOREACH(ipq, &ipr->ip_queue, ipq_next) {
382		char *data;
383		size_t len;
384
385		hlen = ipq->ipq_hdr->ip_hl << 2;
386		len = ntohs(ipq->ipq_hdr->ip_len) - hlen;
387		data = (char *)((uintptr_t)ipq->ipq_hdr + hlen);
388
389		bcopy(data, ptr + n, len);
390		n += len;
391	}
392
393	*pkt = ipr->ip_pkt;
394	ipr->ip_pkt = NULL;	/* Avoid free from ip_reasm_free() */
395	*payload = ptr;
396
397	/* Clean up the reassembly list */
398	while ((ipr = STAILQ_FIRST(&ire_list)) != NULL) {
399		STAILQ_REMOVE_HEAD(&ire_list, ip_next);
400		ip_reasm_free(ipr);
401	}
402	return (n);
403}
404
405/*
406 * Receive a IP packet.
407 */
408ssize_t
409readip(struct iodesc *d, void **pkt, void **payload, time_t tleft,
410    uint8_t proto)
411{
412	time_t t;
413	ssize_t ret = -1;
414
415	t = getsecs();
416	while ((getsecs() - t) < tleft) {
417		errno = 0;
418		ret = readipv4(d, pkt, payload, tleft, proto);
419		if (ret >= 0)
420			return (ret);
421		/* Bubble up the error if it wasn't successful */
422		if (errno != EAGAIN)
423			return (-1);
424	}
425	/* We've exhausted tleft; timeout */
426	errno = ETIMEDOUT;
427	return (-1);
428}
429